Digital broadcasting transmission capable of improving receiving and equalizing performance and signal processing method thereof

ABSTRACT

A digital broadcast transmitting system and a signal processing method thereof that improves the receiving performance of the system. A digital broadcast transmitter includes a randomizer to receive and randomize a transport stream into a specified position of which stuff bytes are inserted, a replacement sequence generator to generate known data including a predefined sequence, a stuff-byte exchange unit to insert the known data into the specified position of the transport stream into which stuff bytes are inserted, an encoder to encode the transport stream output from the stuff-byte exchange unit for an error correction, and a transmission unit to modulate the encoded transport stream, RF-convert the modulated transport stream and transmit the RF-converted data. The digital broadcast receiving performance is improved even in an inferior multi-path channel by detecting the known data from the received transmission and using the known data for synchronization and equalization.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT International PatentApplication No. PCT/KR 2005/001940 filed Jun. 23, 2005, and KoreanPatent Application No. 2004-47153 filed Jun. 23, 2004 in the KoreanIntellectual Property Office, the disclosures of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An aspect of the present invention relates to a digital broadcastingtransmission/reception system, and more specifically, to a digitalbroadcasting transmission system generating stuff byte in a MovingPicture Experts Group-2 transport stream (MPEG-2 TS), and operating andtransmitting a pattern of known data using the stuff byte to improvereception performance and equalization performance of a reception systemand a signal processing method thereof.

2. Description of the Related Art

The Advanced Television Systems Committee Vestigial Sideband (ATSC VSB)method, a U.S.-oriented terrestrial waves digital broadcasting system,is a single carrier method that uses a field sync by 312 segment unit.Accordingly, reception performance is not good in poor channels,especially in a Doppler fading channel.

FIG. 1 is a block diagram of a transmitter/receiver of a generalU.S.-oriented terrestrial waves digital broadcasting system according tothe ATSC digital television (DTV) standards.

The digital broadcasting transmitter of FIG. 1 has a data randomizer(110) for randomizing an MPEG-2 TS, an Reed-Solomon (RS) encoder (120)of a concatenated coder form for correcting errors generated bychannels, an interleaver (130), and a ⅔ rate trellis encoder (140). Theencoded data is mapped in 8 level symbols and field syncs and segmentsyncs are inserted into the data as shown in FIG. 2. After that thefield syncs and the segments syncs are inserted, pilots are insertedinto the data, the data is then VSB-modulated, upconverted into RF andtransmitted.

Meanwhile, the digital broadcasting receiver of FIG. 1 lowers the RFsignal to baseband, demodulates and equalizes the lowered signal,performs channel decoding, and restores the original signal in a reverseorder of the digital broadcasting transmitter.

FIG. 2 shows a vestigial sideband (VSB) data frame of the U.S.-orientedDTV system. In FIG. 2, one frame consists of two fields and each fieldincludes 312 data segments and a field sync segment. Each segment alsohas segment syncs of four symbols and data symbols of 828 symbols.

As shown in FIG. 1, the digital broadcasting transmitter randomizes theMPEG-2 TS through the randomizer (110). The randomized data isouter-coded through the RS encoder (120) which is an outer coder, andthe outer-coded data is dispersed through the interleaver (130). Theinterleaved data is inner-coded by 12 symbol unit through the trellisencoder (140), and the inner-coded data is mapped in an 8 level symboland the field syncs and segment syncs are inserted as shown in FIG. 2.Thereafter, the data includes DC offset to generate the pilot, and thedata is VSB-modulated, upconverted to an RF signal and transmitted.

Meanwhile, the digital broadcasting receiver of FIG. 1 converts an RFsignal received through a channel into a baseband signal through atuner/IF (not shown). The baseband signal is synchronization-detectedand demodulated through a demodulator (210), and any distortion bymulti-path channel is compensated through an equalizer (220). Theequalized signal is error-corrected and decoded into symbol data througha Viterbi decoder (230). The decoded data, which has been dispersed bythe interleaver (130) of the transmitter, is rearranged through adeinterleaver (240), and the deinterleaved data is error-correctedthrough an RS decoder (250). The error-corrected data is de-randomizedthrough a derandomizer (260) and output into an MPEG-2 TS.

In the VSB data frame of the US-oriented terrestrial waves DTV system ofFIG. 2, one segment corresponds to one MPEG-2 packet. In FIG. 2, thesegment sync and field sync, which are sync signals, are used forsynchronization and equalization. The field sync and segment sync areknown sequences and used as training data in the equalizer.

The VSB method of the U.S.-oriented terrestrial waves digital televisionsystem of FIG. 1 is a single carrier system and has the capacity toremove multipath in a multipath fading channel with Doppler. However, ifthe known sequence such as a field sync is used a lot, it is easier toestimate the channel and compensate the signal distorted by a multi-pathin the equalizer using the known sequence.

However, as shown in the VSB data frame of the U.S.-oriented terrestrialwaves digital television system of FIG. 2, a field sync which is a knownsequence appears in every 313th segment. This is not frequent so thecapacity to remove the multipath and equalize the received signal usingthis known sequence, is low.

SUMMARY OF THE INVENTION

An aspect of the present invention is to provide a digital broadcastingtransmission system to improve reception performance and equalizationperformance of a reception system by adding a predefined known sequence,manipulating a pattern and transmitting a signal in a transmissionsystem and a signal processing method, and a digital broadcastingreception system corresponding to the above and a signal processingmethod thereof.

A digital broadcasting transmitter according to an aspect of the presentinvention includes a randomizer for receiving and randomizing a datastream including stuff bytes at a certain location, a sequence providerfor generating known data having a particular sequence to replace thestuff bytes, a stuff byte replacer for inserting the known data at thelocation of the randomized data stream where the stuff bytes areinserted, an encoder for encoding the data stream output from the stuffbyte replacer for error-correction, and a transmission part formodulating, RF-converting and transmitting the encoded data stream.

According to another aspect of the present invention, the data streamincludes information of the certain location where the stuff bytes areinserted.

According to another aspect of the present invention, the information ofthe location is inserted prior to a location where the stuff bytes areinserted and the information includes information of the length of thestuff data.

According to another aspect of the present invention, the transmitterfurther includes a control signal generator generating a control signalto control the stuff byte replacer to insert the known data at thelocation according to the information.

According to another aspect of the present invention, the encoderincludes an RS encoder for adding a parity of certain bytes to correcterrors generated by channels, an interleaver for interleaving the dataadded with the parity in a certain pattern, and a trellis encoder fortrellis-encoding the interleaved data.

According to another aspect of the present invention, the trellisencoder has a memory element for trellis encoding operation andinitializes the memory element from the location inserted with the knowndata for trellis-encoding.

According to another aspect of the present invention, the transmitterfurther includes a packet buffer receiving and temporarily storing thedata stream from the RS encoder.

According to another aspect of the present invention, the packet bufferreceives the data altered according to the initialization of the memoryelement from the trellis encoder and updates the stored data.

According to another aspect of the present invention, the transmitterfurther includes a RS re-encoder & replace parity for RS-encoding theupdated data input from the packet buffer, generating the alteredparity, outputting the parity to the trellis encoder and replacing theparity added by the RS encoder.

According to another aspect of the present invention, the interleaveroutputs known data, inserted at the same location of a plurality ofdifferent data streams output from the RS encoder in continuous datastreams.

According to another aspect of the present invention, the transmissionpart modulates the data in VSB modulation.

According to another aspect of the present invention, a signalprocessing method for digital broadcasting transmission includesreceiving and randomizing a data stream inserted with stuff bytes at acertain location, generating a predefined particular sequence as knowndata, inserting the known data at the location inserted with the stuffbytes of the randomized data stream, encoding the data stream insertedwith the known data for error-correction, and modulating, RF-convertingand transmitting the encoded data stream.

According to an aspect of the present invention, a digital broadcastingtransmitter generates and inserts stuff bytes in an MPEG-2 TS packet andtransmits the inserted stuff bytes as known data, and a digitalbroadcasting receiver detects and uses the known data so that thedigital broadcasting reception performance can be improved in poormultipath channels.

In addition, a sequence of the known data is manipulated in a pattern toimprove performance of the equalization so that equalization performanceand reception performance can be improved.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a block diagram illustrating a transmitter of a generalU.S.-oriented terrestrial digital broadcasting system;

FIG. 2 is a view of a frame structure of ATSC VSB data;

FIG. 3 is a view of a frame structure of a TS packet;

FIG. 4 is a view of a frame structure of a TS packet including a stuffbyte;

FIG. 5 is a block diagram of a digital broadcasting transmission systemaccording to an embodiment of the present invention;

FIG. 6 is a view of a format of the data input to the randomizer of FIG.5;

FIG. 7 is a view of a format of the data output from the randomizer ofFIG. 5;

FIG. 8 is a view of a format of the data output from the RS encoder ofFIG. 5;

FIG. 9 is a view of a format of the data output from the datainterleaver of FIG. 5;

FIG. 10 is a view of a format of the data output from the trellisencoder of FIG. 5;

FIG. 11 is a view of a format of the data output from an RS re-encoderaccording to trellis initialization of the known sequence section; and

FIG. 12 is a block diagram illustrating a digital broadcastingtransmission system according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

FIG. 3 shows a frame structure of a Transport Stream (TS) packet andFIG. 4 shows a frame structure of a TS packet including a stuff byte.The TS packet of FIG. 4 includes an MPEG-2 header, an adaptation fieldand payload data. According to an aspect of the present invention, stuffbytes are inserted in the TS packet as illustrated in FIG. 4 so that allthe TS streams have adaptation fields.

That is, the MPEG-2 TS packet of FIG. 4 is an MPEG-2 packet of 188 bytesand consists of an MPEG-2 header, an adaptation field and ES or payloaddata. The header includes 4 bytes with MPEG syncs, the adaptation fieldincludes an adaptation field length section of 1 byte indicating thelength of the adaptation field, an adaptation field data section havingother information of 1 byte and stuff bytes of N bytes, and the payloaddata includes ES data of 188-(4+2+n) bytes.

FIG. 5 is a block diagram illustrating a digital broadcastingtransmission system according to an embodiment of the present invention.In FIG. 5, the digital broadcasting transmitter receives an MPEG-2packet TS having the packet structure of FIG. 4 through a TS multiplexer(not shown).

In FIG. 5, the digital broadcasting transmitter has a data randomizer(310) randomizing the input TS stream, a stuff byte replacer (315)replacing the stuff byte of the randomized data with a particularsequence, an RS encoder (320) constructing the data output from thestuff byte replacer (315) in the concatenated code form to correcterrors generated by channels, an interleaver (330) interleaving thedata, a packet buffer (325) storing the RS-encoded reference data toinitialize a memory of a trellis encoder (340) and replacing theprevious value with an initialized value, an RS re-encoder & replaceparity (335) performing RS-encoding using the altered value, generatinga parity and inputting the parity to the trellis encoder (340), thetrellis encoder (340) converting the interleaved data into symbols andperforming ⅔ rate trellis encoding and 8 level symbol mapping, amultiplexer (350) inserting field syncs and segment syncs as shown inFIG. 2, a transmission part (360) for inserting a pilot, performingVSB-modulation, upconverting the data into RF and transmitting the data,and a control signal generator (370) generating a signal to control dataprocessing.

Meanwhile, an MPEG-2 packet TS having the packet structure of FIG. 4 isinput to the randomizer (310) through the TS multiplexer (not shown),randomized, replaced with a particular sequence for the stuff bytes bythe stuff byte replacer (315) and output. The output data is outer-codedthrough the RS encoder (320) to correct errors by channels and theouter-coded data is dispersed through the interleaver (330).

Subsequently, the interleaved data is inner-coded by a 12 symbol unitthrough the trellis encoder (340). The inner-coded data is mapped in 8level symbols and the field syncs and segment syncs are inserted asshown in FIG. 10 by the multiplexer (350). Thereafter, the data includesa DC offset to generate a pilot and the data is VSB-modulated,up-converted into RF and transmitted.

Meanwhile, the control signal generator (370) detects the adaptationfield length of FIG. 4, and generates and outputs a flag signal toindicate the location of stuff bytes or known sequence data based on thedetected result.

Further, in FIG. 5, the trellis encoder (340) performs an initializationof 12 trellis encoder at the beginning location of the known sequence,for example, in order for the value of the memory element of the encoderto become ‘00’. The sequence altered by the initialization replaces thevalue stored in the packet buffer (325) and the new parity generated bythe RS re-encoder & replace parity (335) replaces the value of theoriginal parity location input to the trellis encoder (340) so that theinitialization is performed.

FIG. 6 to FIG. 10 show data formats while an MPEG-2 packet with stuffbytes passes through channel encoder blocks of the digital broadcastingtransmitter.

FIG. 6 shows a format of the data input to the randomizer (310) and FIG.7 shows a data format after replacing n stuff bytes of the randomizeddata with particular sequence data. FIG. 8 shows a data format of theRS-encoded data added with RS parity and FIG. 9 shows a data format ofthe data output from the interleaver (330).

Further, FIG. 10 shows a format of the 12 symbol interleaved data outputfrom the trellis encoder (340). FIG. 11 is a format of the data whoseparity is restructured by the RS re-encoder & replace parity (335) ofFIG. 3. In FIG. 10, one field includes six convolutional interleavers,so there are six sequences with stuff bytes. That is, if a TS includesstuff bytes of 10 bytes, one field has known sequences of 10*6=60. Ifthe trellis encoder (340) is initialized at the beginning location ofthe known sequence, the output parity of the RS encoder (320) is alteredby the value of initialization and trellis encoding is performed byupdating with the altered parity.

The MPEG-2 packet of FIG. 6 is dispersed by 52 units by the interleaver(330) as shown in FIG. 9. The data located in the same byte of theMPEG-2 packet constructs the same column as shown in FIG. 9 after datainterleaving. Additionally, the interleaved data are12-symbol-interleaved by the trellis encoder (340) as shown in FIG. 10.That is, the data of the same location in MPEG-2 packets constructalmost one data segment as shown in FIG. 10 after trellis encoding.Therefore, if a particular part of an MPEG-2 packet is continuouslyadded with stuff bytes, randomized, replaced with a particular sequenceand trellis-encoded, the stuff bytes form one data segment which is aknown signal and a digital broadcasting receiver uses the known signalto improve reception performance.

FIG. 11 shows a data format after RS re-encoding and parityrestructuring by the RS re-encoder & replace parity (335) of FIG. 5.That is, if the trellis encoder (340) is initialized at the beginninglocation of a sequence of the known symbol, output parity of the RSencoder (320) is altered by the value of the initialization and trellisencoding is performed by being updated with the altered parity so thatthere is no problem in decoding of the RS decoder of a digitalbroadcasting receiver which will be briefly described below. That is,the trellis encoder is initialized in order for the trellis-encoded datato form a regular sequence during the known symbol sequence section, RSencoding is performed to replace the data of the initialization locationso that parity is altered and the altered parity replaces the originalparity. FIG. 11 shows the data format.

In a digital broadcasting transmitter, if the information on the numberof stuff bytes is inserted in a reserved section of a field sync datasegment section, a known symbol number detector (not shown) of a knownsymbol location detector/known data output (not shown) of the digitalbroadcasting receiver detects the information on the number of the knowndata, a segment flag generator (not shown) and trellis interleaver (notshown) find the location information of the known symbol based on theinformation, and a known data extractor (not shown) outputs and uses theknown data from the acquired information to improve receptionperformance of the digital broadcasting receiver. As the location ofstuff bytes is always fixed, if the information on the number of thestuff bytes is acquired, the segment flag generator (473) and trellisinterleaver (475) can be implemented using a counter and control logic.

FIG. 12 is a block diagram illustrating a digital broadcastingtransmission system according to another embodiment of the presentinvention. In FIG. 12, the digital broadcasting transmitter has arandomizer (510) for randomizing data of the input TS stream, a stuffbyte replacer (515) for replacing the stuff byte of the randomized datawith a particular sequence generated in a replacement sequence generator(513), an RS encoder for constructing the data output from the stuffbyte replacer (515) in the concatenated code to correct errors generatedby channels, an interleaver (530) for interleaving the data, a packetbuffer (525) for storing the RS-encoded reference data to initialize amemory of the trellis encoder (540) and replacing the stuff byte with aninitialized value, an RS re-encoder & replace parity (535) forperforming RS-encoding using the altered value to generate parity andinputting the data to the trellis encoder (540), the trellis encoder(540) for converting the interleaved data into a symbol and performing ⅔trellis encoding and 8 level symbol mapping, a multiplexer (550) forinserting a field sync and segment sync as in the data format of FIG. 2,a transmission part (560) for inserting a pilot, performingVSB-modulation, converting the data into RF and transmitting the data,and a control signal generator (570) for generating a signal to controldata processing.

The function and operation of each component of the digital broadcastingtransmission system of FIG. 12 are similar to the components of FIG. 5.Therefore, a detailed description of the function and operation isomitted and the difference will be described.

A stuff byte replacer (515) replaces stuff bytes of the data randomizedby the randomizer (510) with a particular sequence and outputs the data.In this case, a pattern of the particular sequence may be adjusted inorder for the symbols mapped through the trellis encoder (540) to beoperated by an equalizer in a receiver.

Therefore, according to another embodiment of the present invention, thedigital broadcasting transmitter further includes the replacementsequence generator (513) for generating a particular sequence to replacethe stuff bytes and providing the particular sequence to the stuff bytereplacer (515) in order for the pattern of the known sequence generatedby replacing the stuff bytes to operate the equalizer.

According to another embodiment of the present invention the replacementsequence generator (513), and a parity reconstruction (535) of thetransmitter operate differently from the digital broadcastingtransmission system of FIG. 5.

The replacement sequence generator (513) includes a memory (not shown)for storing the particular sequence to replace the stuff bytes in thestuff byte replacer (515) and a circuit (not shown) for controlling amemory address.

If the sequence pattern of the known data of FIG. 9 and FIG. 10 has arandom pattern without DC offset, operation performance of the equalizercan be improved. Accordingly, the replacement sequence generator (513)may preferably generate a particular sequence to replace the stuff bytesso that the sequence pattern of the known data mapped after trellisencoding of the trellis encoder (540) in the stuff byte replacer (515)has the random pattern without DC offset.

First, in order for the sequence of the known data to have a desirablepattern, the memory value of the trellis encoder (540) has to beinitialized.

The compatibility is maintained with the existing receiver and thememory value of the trellis encoder (340) is initialized by the packetbuffer (325) and RS re-encoder & replace parity (335) of FIG. 5.

According to a method of an embodiment of the present invention, themethod initializes the memory value of the trellis encoder (340) of partof the stuff bytes according to the number of stuff bytes instead of theentire stuff bytes in order to be compatible with the existing receiver.Accordingly, the initialized stuff bytes can limitedly have a desirablepattern.

Therefore, in another embodiment of the present invention, the functionof initializing a memory value of the trellis encoder (540) for theentire stuff bytes, is added to the RS re-encoder & replace parity(535). That is, the RS re-encoder & replace parity (535) is compatiblewith the existing receiver and initializes the memory value of thetrellis encoder (540), according to an embodiment of the presentinvention, depending on initial set-up and user choice, and ignores thecompatibility with the existing receiver and initializes the memoryvalue of the trellis encoder (540) for the entire stuff bytes.

The value of the part that initializes the memory value of the trellisencoder of the particular sequence, which is generated in thereplacement sequence generator (513) and replaces the stuff bytes in thestuff byte replacer (515), can be any value. The replacement sequencegenerator (513) considers the symbol value, mapped aftertrellis-encoding according to the memory value to have the desiredpattern by the sequence of the known data wants after theinitialization, and generates the particular sequence to replace thestuff bytes.

The replacement sequence generator (513) stores the above particularsequence in the memory (now shown) and is controlled to adjust the syncby a control signal generator (570). Accordingly, the sequence of theknown data improves the operation performance of the equalizer and thereceiver.

As above-described, stuff bytes are generated and inserted in an MPEG-2TS packet, the inserted stuff bytes are transmitted as known data fromthe digital broadcasting transmitter and the digital broadcastingreceiver detects and uses the known data so that reception performancesuch as sync acquisition and equalization performance can be improved.

In addition, the sequence of the known data improves the operationperformance of the equalizer so that the reception performance of thereceiver can also be improved.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A digital broadcasting transmitter, including: a randomizer receivingand randomizing a transport stream including stuff bytes at a certainlocation; a sequence provider generating known data having a particularsequence to replace the stuff bytes; a stuff byte replacer inserting theknown data at the location of the randomized transport stream where thestuff bytes are inserted; an encoder encoding the transport streamoutput from the stuff byte replacer for error-correction; and atransmission part modulating, RF-converting and transmitting the encodedtransport stream.
 2. The transmitter as claimed in claim 1, wherein thetransport stream includes information of the certain location where thestuff bytes are inserted.
 3. The transmitter as claimed in claim 2,wherein the information is inserted in the transport stream prior to thelocation where the stuff bytes are inserted and includes lengthinformation of the stuff data.
 4. The transmitter as claimed in claim 3,further including a control signal generator generating a control signalto control the stuff byte replacer to insert the known data at thelocation according to the information in the transport stream.
 5. Thetransmitter as claimed in claim 1, wherein the encoder includes: an RSencoder adding a parity of certain bytes to correct errors generated bychannels; an interleaver interleaving the data added with the parity ina certain pattern; and a trellis encoder for trellis-encoding theinterleaved data.
 6. The transmitter as claimed in claim 5, wherein thetrellis encoder has a memory element for trellis encoding operation andinitializes the memory element from the location inserted with the knowndata for trellis-encoding.
 7. The transmitter as claimed in claim 6,further including a packet buffer receiving and temporarily storing thetransport stream from the RS encoder.
 8. The transmitter as claimed inclaim 7, wherein the packet buffer receives the data altered accordingto the initialization of the memory element from the trellis encoder andupdates the stored data.
 9. The transmitter as claimed in claim 8,further including a RS re-encoder & replace parity for RS-encoding theupdated data input from the packet buffer, generating the alteredparity, outputting the parity to the trellis encoder and replacing theparity added by the RS encoder.
 10. The transmitter as claimed in claim1, wherein the interleaver outputs known data inserted at the samelocation of a plurality of different transport streams output from theRS encoder in continuous transport streams.
 11. The transmitter asclaimed in claim 1, wherein the transmission part modulates the data inVSB modulation.
 12. A signal processing method for digital broadcastingtransmission, including: receiving and randomizing a transport streamincluding stuff bytes at a certain location; generating a predefinedparticular sequence as known data; inserting the known data at thecertain location including the stuff bytes of the randomized transportstream; encoding the transport stream inserted with the known data forerror-correction; and modulating, RF-converting and transmitting theencoded transport stream.
 13. The method as claimed in claim 12, whereinthe encoding of the transport stream includes: adding parity of certainbytes to correct errors generated by channels by RS encoding;interleaving the data added with the parity in a certain pattern; andtrellis-encoding the interleaved data.
 14. The method as claimed inclaim 13, wherein the trellis encoding of the interleaved datainitializes the memory element at the location where the known data isinserted for a predetermined memory element used for trellis encoding sothat the trellis encoding is performed.
 15. The method as claimed inclaim 14, further including: receiving and temporarily storing thetransport stream generated by the RS encoding, receiving the dataaltered according to the initialization of the memory element from thetrellis encoding, and performing an update.
 16. The method as claimed inclaim 15, further including: RS encoding of the encoded data, generatingan altered parity, returning to the trellis encoding, replacing andadding the parity added in the RS encoding, and performing trellisencoding.
 17. The method as claimed in claim 12, wherein in thetransmitting of the encoded transport stream, the data is modulated inVSB modulation.